Improvement in truss-springs



w. PUMEROY.

Improvement in Truss-Springs.

N0. 131,560. Patented Sep.24,18-72.

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Pn'rnn WILLIAM roMnnoY, on NEW YORK, n. Y.

IMPROVEMENT IN TlRUSS-SPRINGS.

Specification forming part of Letters Patent No. 131,560, datedSeptember 24, 1872.

To all whom it may concern: 1

Be it known that I, WILLIAM POMEROY, of the city, county, and State ofNew York, have invented an Improvement in the Construction of Springsfor Trusses and other surgical appliances, of which the following is ,aspecification:

My invention relates to the adjustment of the pressure of the spring ofa truss or other surgical appliance so that more or less force may bebrought to bear at the end of the spring by increasing or diminishingits curvature, and setting it at any required curve without afiectingits general elasticity and power of resisting a strain, by the samemeans enabling it to be fitted to persons of different shapes.

Endeavors have been made to efi'ect this adjustment by making thesprings soft enough to allow of their being bent, in which case,however, the elasticity of the spring is to a great extent lost, and itsresisting power often diminished beyond the degree necessary to make ituseful. A hinge near the middle of the curve, with some mechanism toprevent it from opening outward when adjusted to any particular curve ofthe spring, has also been used, and such a combination is the subject ofa patent granted to me September 17,1867, No. 69,020, part of whichcombination I make use of in the present invention. I have found,however, in practice, that the hinge is objectionable, requiring carefulconstruction with expensive tools by a skilled mechanic to insure itsstrength and accurate working; also, giving to the spring the appearanceof being broken and of weakness at that point, which excites a prejudiceagainst it in the mind of the purchaser; also, when the truss is removedfrom the body the parts of the spring fall together, and the mechanismon the back of the spring is liable to become deranged from its properadjustment. In the case of the eccentric wheel used in the patentreferred to, if it chance to be a little loose on its pivot, then, whenreleased from contact with the block, by the falling together of theparts of the spring it is very liable to be moved around and the properadjustment is lost, impairing the usefulness of the instrument. If itshould be desired to bend the spring at more than one point, and two ormore hinges be used, all the ger of breaking.

In the accompanying drawing, Figure 1 is a plan view of a portion of thespring, showing the mode of construction when it is desired to bend thespring at two points near to each other. Fig. 2 is a section of the samethrough the line a; as of Fig. 1. Figs. 3 and 4 are similar plan andsectional views, showing the construction when the spring is to be bentat one point only.

Similar parts in the several views are designated by like letters andfigures.

For the purpose in view the spring may be formed in two parts, a a,connected at the por tion of the curve where the adjustment is to beeffected, which will ordinarily be at or near the middle by a shortpiece of metal sufficiently flexible and tough to allow of its beingbent without danger of breaking, but at the same time rigid enough toretain its shape and require considerable force to bend it. Untemperedsteel, hard brass, and various compositions of copper, zinc, and othermetals well known in the arts may be used for this purpose. The block 0is securely riveted to the middle of this short piece, which is itselfriveted at each end to the otherparts of the spring, thus connectingthem, and, together with them, forming a continuous spring capable ofbeing bent at the spaces 6 6 between the rivets numbered 2 and 3 andbetween those numbered 4 and 5. The block 0 is made slightly concave ateach end, and provided with notches to fit the serrated edges of theeccentrics d d, which are pivoted on the rivets 2 and 5, the whole beingso arranged that when the spring is opened out to the largest curvedesired the eccentrics shall bear with their shortest radiuses againstthe ends of the block. If, now, the spring is bent at the spaces 0 e theeccentrics may be turned so as to present a longer radius toward theblock or shoulder, preventing the return of the spring to its formercurve. The

serrated edges of the block and eccentric fitting into each otherprevent the latter from turning on its pivot, and when set for any curvethe rigidity of the connecting-strip 1) precludes any'liability of thewheel being released from the shoulder and turned by accident from itsadjustment, as might be the case were a hinge used at this point.

I prefer to provide for bending the spring at two or more points, as theregularity of the curve can thus be better maintained; but if it isdesired to bend it at one place only, the eccentric may be applied atone end of the block, the other end being riveted, together with theconnecting-strip 1), directly to the other arm of the spring, as shownin Figs. 3 and 4.

It is tobe observed that the connectingstrip should be fastened on theouter surface or back of the spring, and not 011 the inside, and shouldbe curved to correspond with the general curve of the spring. If thespring is sufficiently flexible it may be made in one piece, and theblock and wheels riveted directly to it at the proper points. A springof material less rigid than tempered steel. may often be thus used toadvantage, as the space occupied by the block and wheels will be so muchstiffened that such a spring may thus be used in cases for whichotherwise it would not be available. I

I claim as my invention- As a surgical appliance, a spring sufficientlyflexible at one or more points to be bent and provided at such point orpoints with a block and eccentric by which it may be held at the curveto which it is set, substantially as shown, and for the purpose setforth.

WILLIAM POMEROY.

Witnesses:

CHARLES F. MERRISS, DANL. POMEROY.

